• Journal of Life Science
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• v.33 no.2
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• pp.138-148
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• 2023

This study compared and analyzed the antioxidant activities of various organic solvent fractions from the leaves and roots of Peucedanum insolens Kitagawa. For this study, the dried leaves and roots of P. insolens Kitagawa were first extracted using 70% ethanol. The extracts were sequentially sub-fractionated in the order of hexane, chloroform, ethyl acetate, n-butanol, and water. The results revealed that the distribution of total phenolic contents by organic solvent fractions showed the same pattern in both the leaves and roots, with the highest in the ethyl acetate fraction (101.1±1.0 mg vs 71.2±3.4 mg of GAE/mg), but the lowest content in the hexane fraction (9.5±0.2 mg vs 7.5±2.1 mg of GAE/mg). The distribution of total flavonoid content in the organic solvent fractions showed the same pattern as that of total phenolic content. The results of DPPH, ABTS, and FRAP assays showed that the leaf and root extracts exhibited free radical scavenging activity in the same pattern, particularly, the ethyl acetate fraction had the highest activity. These results indicate that not only the roots of P. insolens Kitagawa but also the leaves possess potential substances that exhibit strong antioxidant activity. Significant correlations (R=0.903, p<0.0001, DPPH radical; R=0.891, p<0.001, ABTS radical; R=0.745, p<0.05, FRAP radical) between total phenolics and radical scavenging activities, but also significant correlations (R=0.867, p<0.001, DPPH vs. ABTS radicals; R=0.882, p<0.0001, DPPH vs. FRAP radicals; R=0.973, p<0.0001, ABTS vs. FRAP radicals) between radical scavenging activities were found in the organic solvent fractions. Therefore, as in the roots of P. insolens Kitagawa, the leaves possess strong antioxidant capacity and can be used as the main antioxidant material.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.10
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• pp.1439-1449
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• 2015

Prunus persica Flos (PPF) were investigated for their antioxidant and anti-inflammatory activities to find a natural functional food resource preventing degenerative diseases associated with excessive oxidative stress and chronic inflammation. PPF was extracted using ethanol (EtOH) and then sequentially fractioned by hexane (Hx), dichloromethane (DM), ethyl acetate (EA), n-butanol (BtOH), and water (DW). Contents of total phenolics and flavonoids, as well as 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activities were measured. Anti-inflammatory effects in terms of nitric oxide (NO), prostaglandin (PG) E2, and pro-inflammatory cytokines such as interleukin (IL)-6 and tumor necrosis factor (TNF)-${\alpha}$ production were also measured using LPS-treated RAW 264.7 macrophages. EtOH extract showed relatively high antioxidant activity with high total phenolic (78.1 mg tannic acid/g) and flavonoid contents (55.3 mg rutin/g). EA fraction contained the highest total phenolic and flavonoid contents (394.6 mg tannic acid/g, 253.7 mg rutin/g), followed by BtOH (128.3 mg tannic acid/g, 93.1 mg rutin/g). EA and BtOH fractions and EtOH extract showed higher DPPH radical and ABTS radical scavenging activities than the others (P<0.05). In LPS-treated RAW 264.7 macrophages, EtOH extract ($200{\mu}g/mL$) showed significantly reduced (P<0.05) NO, PGE2, and TNF-${\alpha}$ production levels to 38.5%, 32.3%, and 48.9% of the control, respectively, as well as reduced iNOS and COX-2 protein expression. DM fraction ($50{\mu}g/mL$) showed significantly reduced (P<0.05) NO, PGE2, IL-6, and TNF-${\alpha}$ production levels to 43.5%, 13.3%, 38.7%, and 41.3% of the control, respectively, and EA fraction ($50{\mu}g/mL$) showed significantly reduced NO, PGE2, IL-6, and TNF-${\alpha}$ production levels to 44.8%, 22.4%, 45.7%, and 62.0% of the control, respectively. Taken together, EtOH extract of PPF showed potent antioxidant and anti-inflammatory activities, and EA and BtOH fractions showed comparatively stronger antioxidant activities while DM and EA fractions showed stronger anti-inflammatory activities. It can be concluded that EtOH extract of PPF and its fractions are good candidates as natural resources for the development of anti-oxidative and anti-inflammatory functional food products.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.445-447
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• 2008

본 연구에서는 다중벽 탄소나노튜브용 표면개질제를 리빙라디칼중합법을 통하여 제조하고, 이를 이용하여 표면개질되고 분산제어된 다중벽탄소나노튜브를 제조하고 염료감응형 태양전지의 대전극 재료로 사용하였다. 우선 리빙라디칼중합법 중 nitroxide mediated polymerization (NMP) 기술을 이용하여 poly(maleic anhydride-co-p-acetoxystyrene)-block-poly(p-acetoxystyrene)를 합성하고, 공중합체중의 maleic anhydride기에 이미드화 반응을 통하여 pyrene기를 도입하였다. 공중합체 중의 p-acetoxystyrene 반복단위들은 가수분해 반응을 통하여 p-hydroxystyrene 반복단위로 변환하였으며, 제조된 공중합체의 구조와 열 특성 등을 GPC, GC, $^1H$-NMR, TGA을 통하여 분석하였다. 제조된 공중합체를 이용하여 다중벽 탄소나노튜브의 표면을 polymer wrapping법으로 처리하였고, 표면개질된 탄소나노튜브의 분산성을 다양한 용매에서 비교분석하였다. 표면이 개질되고 페이스트 내에의 분산성이 향상된 다중벽탄소나노튜브를 염료감응태양전지의 대전극 제조에 응용하였으며, 표면처리 및 분산제어 여부에 따른 제작 특성 및 동작특성 등을 평가하였다.

• Journal of Power System Engineering
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• v.15 no.1
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• pp.11-17
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• 2011

본 연구는 라디칼 착화(Radical Ignition이하 RI) 기술을 적용한 부실직분식 CNG(Compressed Natural Gas) 엔진의 구동특성에 관한 것이다. 실험엔진은 단기통 디젤엔진을 개조하여 사용하였으며, 이는 부실식 디젤엔진처럼 연소실이 주실과 부실로 나누어져 있다. 부실에 분사된 CNG는 스파크플러그로 점화하며, 부실로 부터의 연소가스가 주실 희박 혼합기를 시켜 구동하는 엔진이다. RI 기술은 연소속도를 향상시킬 수 있다. 본 연구는 주로 저부하 RI-CNG 엔진의 성능을 연구하였다. 연료분사기간은 9 ms, 공기과잉률은 1.0, 1.2, 1.4로 하였다. 연료분사시기는 엔진의 배가밸브가 닫히는 ATDC $20^{\circ}CA$ 부터 $120^{\circ}CA$ 사이로, $20^{\circ}CA$ 간격으로 지각시켜 가며 실험하였다. 본 연구는 연료분사시기 및 공기과잉률이 연소최고압력 ($P_{max}$), 연소최고압력시기(${\Theta}_{pmax}$), 도시평균유효압력(IMEP), 사이클 변동계수($COV_{imep}$), 연소속도에 미치는 양향 등을 구하고 분석하였다.

• Food Industry And Nutrition
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• v.10 no.2
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• pp.26-31
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• 2005

천연물 유래 기능성 물질 탐색의 일환으로 녹차 추출물의 산업적 적용을 용이하게 하기 위하여 감마선 조사를 병용하여 추출물의 색도 및 라디칼 소거능을 확인하고, 이 추출 파우더를 돈육 패티에 적용하여 항산화, 색도 및 관능검사를 통해 기호도를 조사하였다. 생리활성을 가지는 녹차 잎 추출물의 라디칼 소거능은 $68.2\%$를 나타냈으며, 20 kGy로 조사했을 경우 비조사구와 큰 차이를 나타내지 않았다. 또한, 감마선조사에 의한 색도의 변화는 감마선 조사 후 $L^{\ast}-value$는 증가했고, $a^{\ast}$- 및 $b^{\ast}-value$는 감소하는 것으로 확인되었다. 또한, 녹차 잎 추출 파우더를 돈육 패티에 적용해본 결과 비첨가구에 비해 라디칼 소거능 및 지질 산화를 지연시키며, 조사된 녹차 잎 추출 파우더를 첨가한 돈육패티가 비첨가구 혹은 비조사된 녹차 잎 첨가구에 비해 저장 기간에 따라$L^{\ast}-value$가 높게 나타났다. 또한, 모든 처리구에서 관능적으로도 큰 차이를 보이지 않았다 그러므로 천연물 유래 녹차 추출물 파우더는 돈육 패티의 기능성 첨가제로서 우수하며, 감마선 조사는 녹차 잎 추출 파우더의 산업적 적용을 용이하게 하는 방법 중의 하나라고 사료된다.

• Applied Chemistry for Engineering
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• v.9 no.2
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• pp.294-299
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• 1998

To prove pseudo-homopolymerization(PHP) method indirectly for general system which includes more than one growing radicals per particle, Mayo-Lewis equation of bulk copolymer system was derived form probability equation about instantaneous copolymer composition of emulsion copolymer system during interval II. From Extended Smith-Ewart equation proposed by Ballard et al. in emulsion copolymerization, exact solution was obtained for 0-1 system (i.e., the system containing no more than one growing radical per particle). From the exact solution, average number of radicals per particle and instantaneous copolymer composition were predicted to reach the steady state which a few minutes. So the reliability of this approximation method could by proved directly for 0-1 system. Styrene-butadiene(St-Bu) and Styrene-methyl methacrylate (St-MMA) system were used for model calculations.

• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.04a
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• pp.103.1-103
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• 2003

건조 생약재의 위생화 수단으로 방사선 조사 기술의 적용 가능성을 검토하기 위하여 감마선 조사 생약의 효능 변화유무를 평가하고자 하였다. 본 연구에서는 감마선 조사 시료와 비조사 시료가 생체의 산화적 손상을 억제하는 효과를 비교하기 위하여 방사선에 의한 산화적 손상에 대한 효과를 측정하였다. 감마선 조사(10 kGy) 생약재(H-113) 및 비조사 생약재(H-113) 추출물을 처리하여 배양한 사람 림프구에 방사선을 조사한 후, 단세포전기영동(single-cell gel electrophoresis, SCGE; comet assay)을 수행하여 DNA 상해 경감정도를 관찰하였다. 또한 방사선 조사 및 비조사 생약재(H-113) 추출물을 투여한 생쥐에 8 Gy의 감마선을 조사한 후, 간에서 지질과산화 정도를 비교·관찰하였다. 한편 DPPH 라디칼과 hydroxyl 라디칼 소거효과를 시험관내에서 상호 비교하였다. 감마선 조사 생약재(H-113)는 단세포전기영동, 지질과산화, DPPH 및 hydroxyl 라디칼 소거시험에서 비조사 생약재 (H-113)와 유사한 효과를 나타내어 효능 차이가 인정되지 않았다. 이는 생약재의 여러 가지 고유 효능 중 일부의 안정성을 확인한 것으로 생각되며, 이러한 결과를 바탕으로 감마선 조사 생약재의 고유 효능의 안정성에 관한 체계적인 연구결과를 얻는다면 생약재의 위생화 수단으로 감마선 조사 기술의 이용이 실용화될 수 있을 것으로 사료된다.

• Korean Chemical Engineering Research
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• v.44 no.5
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• pp.483-488
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• 2006

Etching process of PMMA (Polymethyl Methacrylate) on glass surface was investigated by dry etching technique using remote plasma. To determine the etching characteristics, the remote plasma etching was conducted for various process parameters such as plasma power, reaction gas and distance from plasma generation. As the distance from the plasma generation was increased, the etch rate of PMMA was linearly decreased by radical density in plasma. PMMA has removed by reactive radicals in the plasma. The etch rate increased with plasma power because of more reactive radicals. The etch rate and surface roughness of PMMA increased with $O_2$ concentration in the etchant.

• Journal of the Korean Chemical Society
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• v.38 no.1
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• pp.13-20
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• 1994

Substituted anthrasemiquinone radical anions, which were formed by laser flash photoreduction of the substituted anthraquinone (1,4-DHAQ, 1,5-DHAQ, 1,8-DHAQ, 1,8-DCAQ), were studied by the electron spin resonance spectroscopy in the mixed solvents of the 2-propanol and the triethylamine. Hyperfine splitting constants (hfsc) were determined by simulating the ESR spectra. Extended Huckel Molecular Orbital (EHMO) calculations were performed to obtain $\pi$ spin densities for these quinones. The hyperfine splitting constants could be assigned to specific protons on the basis of $\pi$ spin densities.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.2
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• pp.659-669
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• 1996

To clarify the effects of equivalence ratio, initial pressure and temperature on the flame propagation and radicals characteristics, a series of the experimental study were conducted in a quiescent methane-air premixture using a constant volume chamber. The development of the flame was visualized following the start of ignition using high speed schlieren photo and radical images by intensified CCD camera. Combustion pressure and ion current were recorded simultaneously according to the experimental conditions which were equivalence ratio with 0.7 to 1.2, initial pressure with 0.08 MPa to 0.40 MPa and initial premixture temperature with 3l3.2K to 403.2K. The results showed that the flame speed by ion current and mass fraction burned by combustion pressure characterized the effects of flame propagation very well. And increased combustion duration due to lean combustion condition that was below equivalence ratio, 0.8 caused cycle variation and decreasing the power of engine.